The present invention relates to a method and apparatus for positioning a plurality of workpieces in a tightly spaced array within a guide block. More specifically, the present invention relates to a pair of fingers positioned on a robot arm capable of positioning a plurality of workpieces in a closely spaced array.
Currently, in many types of sensitive electronic x-ray machines, a plurality of sensing elements are positioned in a tightly spaced array with minimal spacing between adjacent sensing elements. To construct the array of sensing elements, the individual sensing elements are inserted individually into a guide block. Typically, this process is performed by a human worker, since the tight spacing between the sensing elements requires a degree of manual dexterity currently not available in robotic assembly systems.
During the installation of the sensing elements within the guide block, the human worker typically wiggles the sensing element back and forth until the sensing element slides downward between spacers within the guide blocks. In many applications, the clearance between the edges of the sensing elements and the spacers within the guide block is typically much less than the width of the sensing element, such that the sensing elements tightly fit within the guide block. By wiggling the sensing element as it is pressed downward into the guide block, the human assembly person is able to correctly guide the sensing element into the guide block.
Since the assembly process described above requires a human assembly person, the cost of assembling the array of sensing elements is often quite high. Additionally, the job of assembling the array is a tedious and repetitive process that provides a somewhat undesirable work environment.
In prior attempts to develop an automated system to assemble an array similar to that described above, it was found that available robot assembly arms proved to be too inflexible when inserting the delicate sensing elements. For example, when the previously available robot arm attempted to insert the sensing elements into the tightly spaced guide blocks, the robot arm would simply press the sensing element downward into the guide block. Because of the tight spacing within the guide block, the sensing element would pinch and prevent the sensing element from being inserted into the guide block. When the robot arm would continue to apply the insertion force, the robot arm would oftentimes fracture the brittle and thin sensing element. Therefore, a need exists for an automated assembly method and apparatus for inserting a plurality of delicate sensing elements into a tightly spaced array within a guide block.
It is an object of the present invention to provide an automated assembly mechanism capable of inserting delicate workpieces into a tightly spaced guide block. It is a further object of the invention to provide an assembly station in which a robot arm including specially designed gripper fingers select an individual sensing element from a supply and insert the individual sensing element into a guide block. It is a further object of the invention to provide a method of inserting the sensing element into the guide block by alternatively rotating the sensing element in opposed directions while applying an insertion force in a direction to force the sensing elements into the guide block. It is a further object of the invention to provide a pair of gripper fingers on the robot arm that include a resilient mounting structure that allows the gripper fingers to separate when rotation of the sensing element is restricted to prevent fracture of the sensing element. It is a further object of the invention to provide a method of assembling a plurality of sensing elements in a spaced array in which the space between the individual sensing elements is less than the width of the gripper fingers.